You can also try this site:
<a href="http://www.webopedia.com/" target="_blank">Webopedia</a>
<a href="http://www.webopedia.com/TERM/m/mainframe.html" target="_blank"><b>Mainframe search</b></a>
<a href="http://www.webopedia.com/TERM/s/supercomputer.html" target="_blank"><b>Supercomputer search</b></a>
The main diffrence is:
The chief difference between a supercomputer and a mainframe is that a supercomputer channels all its power into executing a few programs as fast as possible, whereas a mainframe uses its power to execute many programs concurrently.

